Duing an migration from OCS 2007 R2 to Lync the Dialin Conference number was removed in OCS, however it was still present in Lync.
This was showen on the Dialin Page in Lync, where the last entry is the OCS 2007 R2 number.
It’s not possible to remove or change OCS conference numbers in Lync or vice versa. The number has to be moved to Lync if it shall be handle correctly.
So to remove the old numer you have to find the SIP address for the “correct” Lync dialin number:
Then run this command
Set-CsDialInConferencingAccessNumber “Sip Address” –ScopeToSite
This will do the trick and the OCS number is removed in the Lync dialin page.